Overview

CT findings suggestive of atelectasis include hilar displacement, elevation of ipsilateral diaphragm, rib crowding, displacement of fissures, and compensatory hyperlucency of the remaining lobes. CT findings associated with complete atelectasis of an entire lung include opacification of the entire hemithorax and ipsilateral shift of the mediastinum. Collapse of different parts of the lung have their own characteristic appearance. For example, a collapsed right middle lobe has a tilted icecream sign which appears as a triangular opacity against the border of the right heart with a laterally pointed apex. On the other hand, RUL collapse appears as a right paratracheal opacity, with a concave lateral appearance of the minor lung fissure.

CT

CT scan may be helpful in the diagnosis of atelectasis. Findings on CT scan suggestive of atelectasis include direct and indirect signs of lobar collapse:[1]